The supporters of HS2 argue that apart from the saving of time between the major cities the line would serve (and Heathrow Airport) it would also take pressure off existing routes the line will duplicate. This, it is argued, will be of particular benefit to places along the existing routes which suffer poor services as lines are kept clear for express trains between major cities.
Rail travel is on the increase, there are more passenger miles travelled each year than at any time since 1945. Many parts of the existing rail system are running very close to maximum capacity. It is not easy to increase capacity a sit involves lengthening trains and platforms, signalling for shorter headway between trains, platform capacity at terminal stations and conflicting train movements at junctions. On some routes these options are not available, or where they have been taken already, there is no scope for further capacity raising measures.
The only example of competition between a high speed route and the 'historic' railway is between Kent and London. This can be illustrated by the Ashord International - London peak services.
AI to London Charing Cross: £25.40 79 minutes
AI to London Victoria: £25.40 98 minutes
AI to London St Pancras (HS) £30.40 35 minutes
Off-peak fares are £19.40, £24.00 and £28.80 respectively. The cost of an off-peak fare to London Victoria seems high at £24.00. Should I wish to travel to the Victoria area of London does the cost saving outweigh the additional cost of travel to Victoria + Underground fare and travel time between the two London stations? Indeed would the time differential between the two routes be much after Underground travel time has been added? If the cost to travel to Victoria was £19.40 that would be my choice.
For anyone wishing to travel to the area served by Charing Cross it seems pointless to use the HS route as all the time 'saved' on the HS route would be lost on the Underground and I doubt if even South Eastern would dare raise the price of a ticket to Charing Cross to make it less competitive.